Hybrid hydraulic-electric engine

ABSTRACT

An automobile drive engine is described having an electric motor with two hydraulic pumps fixedly mounted on the center shaft of the motor. The smaller sized hydraulic pump is mounted on one side of the electric motor and the larger pump is mounted on the other side of the electric motor. The two hydraulic pumps are connected by hydraulic hoses which allow hydraulic fluid to circulate between the two pumps. As the electric motor begins to turn, it causes the impeller blades of the larger hydraulic pump to rotate forcing hydraulic fluid through the hose thereby building pressure on the impeller blades of the smaller hydraulic pump. The smaller hydraulic pump then begins to rotate. Because of the ratio of sizes, the smaller hydraulic pump begins to rotate much faster increasing the torque and/or speed produced by the electric motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

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STATEMENT REGUARDING FEDERALLY SPONSERED RESEARCH OR DEVELOPMENT

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REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

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BACKGROUND OF THE INVENTION

This invention relates to a hybrid hydraulic-electric engine and inparticular to an electric drive engine whose torque characteristicsand/or speed are varied by hydraulic pumps mounted on the drive shaft ofthe electric engine.

Over the years, many gearing configurations have been proposed to modifythe torque and/or speed characteristics of electric motors. For example,U.S. Pat. No. 6,726,588 describes a differential electric engine whereinthe rotational torque of the output drive shafts of the engine iscontrolled by first and second differential stages coupled to theshafts. This configuration is a mechanical gear control of the motoroutput as compared to the hybrid control system of this invention.

U.S. Pat. No. 5,492,189 discloses a propulsion system having first andsecond drive shafts connected to a steady state internal combustionengine and a transitionally operating driving system. The combinationengine and driving system are mounted on different shafts of a planetarygear to permit continuous variations of the output speed, independent ofthe applied torque.

In U.S. Pat. No. 6,662,905, an elevator control is described which usesthe counterweight as a hydraulic plunger to assist in moving the carupward and downward. The counterweight plunger supplements a fluidcirculation circuit comprising at least a driving pump coupled tovalves. The fluid control does not adjust the speed of the lift motor,other than by varying the load placed on the motor.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a hybrid hydraulic-electric motor havinga central shaft which is driven by the motor. A forward positionedhydraulic pump and a rearward positioned hydraulic pump are fixedlymounted on the central shaft and are interconnected by hydraulic hoseswhich permit fluid to circulate between the two hydraulic pumps. As theelectric motor turns, it rotates impellers within the forward hydraulicpump thereby applying a rotational force to the rearward hydraulic pumpto augment the torque of the electric motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a hybrid hydraulic-electric engine in accordance with thisinvention.

FIG. 2 is a graphical illustration of the relationship between torqueand EMF applied to a standard electric engine.

FIG. 3 is a graphical illustration of the relationship between torqueand EMF of a hybrid hydraulic-electric engine in accordance with thisinvention.

FIG. 4 is a flow chart showing force flow in the hybridhydraulic-electric engine of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring more particularly to FIG. 1, an electric motor 10 is fixedlymounted on a central shaft 11 and is powered by a battery 12 throughstarting switch 13. A forward hydraulic pump 14 is mounted on one sideof shaft 11 and contains a plurality of impeller blades 15 which arerotated by shaft 11 upon energization of electric motor 10. Rotatingimpeller blades 15 pump hydraulic fluid from forward hydraulic pump 14through hydraulic hose 16 to apply hydraulic pressure on impeller blades17 of rearward hydraulic pump 18. Impeller blades 17 are fixedly mountedon shaft 11 and the hydraulic pressure on impeller blades 17 augmentsthe torque produced by electric motor 10 on shaft 11. A second hydraulichose 19 returns hydraulic fluid from rearward pump 18 to forwardhydraulic pump 14. Central shaft 11 is particularly adapted to power aload such as an automobile (not shown) requiring a large torque uponenergization of electric motor 10. For optimum performance, a powerratio between forward hydraulic pump 14 and rearward hydraulic pump 18should be at least 10-1.

FIG. 2 shows the torque produced by a standard electric motor withoutthe hydraulic assist of this invention as an electromagnetic force (EMF)is applied to the coils of the motor. The torque produced on the motorshaft varies in a substantially linear fashion with the magnitude of theapplied EMF. As shown in FIG. 3, the hybrid hydraulic-electric engineshown in FIG. 1 initially has a relatively slower increasing torque dueto the additional load placed on the motor by forward hydraulic pump 14.The turning of impeller blades 15 in forward hydraulic pump 14 forceshydraulic fluid into rearward hydraulic pump 18 to supplement the torqueon shaft 11. With a hydraulic ratio of at least 10-1 the output torqueon central shaft 11 increases parabalicly to produce a high torquewithin a short period following energization of motor 10. The force flowin hybrid hydraulic-electric engine 10 is shown in the flow diagram ofFIG. 4.

1) A hybrid hydraulic-electric engine comprising An electric motor, Acentral shaft driven by said electric motor, A first hydraulic pumpfixedly mounted on said central shaft adjacent one side of said electricmotor, Said first hydraulic pump having a plurality of impeller bladesto pump fluid within said pump through an outward orifice of said pump,A second hydraulic pump mounted on said central shaft on the side ofsaid electric motor remote from the first hydraulic pump, Fluid conveyormeans for transporting hydraulic fluid from said first hydraulic pump tosaid second hydraulic pump and Second fluid conveying means fortransporting hydraulic fluid from said second hydraulic pump to saidfirst hydraulic pump. 2) A hybrid hydraulic-electric engine pumpaccording to claim 1 wherein the power ratio between the first andsecond hydraulic pumps is at least 10-1. 3) A hybrid hydraulic-electrichybrid engine according to claim 2 wherein the central shaft rotates thewheels of an automobile.